Proper leather shoes

I always use shoe trees for my proper leather shoes, you get more out of them if you treat them well when not wearing the. Buy cedar wooden ones, always.

Shoe trees: always cedar, always unvarnished.

When they start to lose their "cedar aroma" give them a once over with some fine sandpaper.

Why 'must' they be cedar? I get the aroma repels moths but do their eggs attack leather, or is it just another line of defence?